In internal combustion engines, both the efficiency and pollution characteristics of the engine are highly dependent on the efficient combustion of the fuel-air mixture in the cylinders. Inefficient combustion results in loss of power (i.e., efficiency) and greater pollution due to incomplete fuel usage.
In conventional gas engines, the fuel-air mixture is ignited by a spark plug that provides a spark to the mixture when a high voltage (i.e. 10-30 kV) is applied across a spark gap of a spark plug. The application of the high voltage is timed for when the cylinder volume (and therefore the fuel-air mixture) is close to as low a volume as possible, i.e., close to Top-Dead-Center (TDC) or just before or after TDC. In that characteristic location, the fuel-air mixture is compressed as much as possible and the spark from the spark gap can ignite a flame that propagates through the volume of the cylinder. As is well known, multiple cylinder engines operate by timing the combustion of a fuel-air mixture in each cylinder appropriately.
In a conventional diesel engine, the fuel-air mixture is ignited by compression of the mixture in the cylinder to reach a flash point. Glow-plugs or other devices may be utilized to assist combustion, at least until the engine is warm enough that the fuel ignites at or near the end of the compression stroke alone.
Utilization of RF or microwave energy to enhance combustion has been proposed. (See, e.g., U.S. Pat. No. 3,934,566 to Ward). In the proposal of Ward, a continuous wave (CW) of RF or microwave energy can be supplied through a spark plug or glow plug while ignition of the fuel-air mixture is accomplished conventionally, i.e. by applying a high voltage across a spark-plug gap or by compressing the fuel-air mixture to its ignition point. Such a system is highly complicated as it requires both a microwave system and a conventional high-voltage delivery system to the spark plug.
Therefore, there is further need for systems that enhance the combustion of a fuel-air mixture in an internal combustion engine.